In general, as methods for manufacturing silicon wafers, a Floating Zone (FZ) method or a Czochralski (CZ) method is mainly used. Because growing a monocrystal silicon ingot using the FZ method is plagued by several problems, such as difficulty in manufacturing large-diameter silicon wafers and considerably expensive process costs, growing a monocrystal silicon ingot using the CZ method is prevalent.
With such a CZ method, after polycrystalline silicon is charged into a quartz crucible and is melted by heating a graphite heating element, a seed crystal is submerged into molten liquid silicon, acquired as a result of melting, to cause crystallization at the interface of the molten liquid silicon, and is then pulled while being rotated, thereby completing the growth of a monocrystal silicon ingot. Thereafter, the grown monocrystal silicon ingot is subjected to slicing, etching, and polishing so as to be shaped into a wafer.
A common method of analyzing a defect region of a wafer includes a process of evenly contaminating the surface of a wafer using a metal solution. Thereafter, a defect region is distinguished using a phenomenon in which the degree of gettering of the metal is different per defect regions due to diffusion of point defects within a temperature range capable of achieving oxygen precipitation. This conventional method of analyzing a defect region of a wafer has a merit in that it is possible to visually and clearly distinguish a defect region and in that it is easy to quantify the area of the defect region. However, when the analysis of a defect region of a wafer is performed using this conventional method, equipment for contaminating metal and etching equipment are additionally required and results after heat treatment may vary greatly depending on the contamination concentration and contamination method of the surface of the wafer. Further, when a worker observes a defect region with the naked eye using highlight, an error may occur.
When a Cu contamination method (or a Cu Haze method), which is one of conventional crystal defect evaluation methods, is used, local variation due to a difference in concentration between point defects cannot be excluded, and thus there is a problem in that a defect region cannot be accurately distinguished.